Imaging devices having autofocus control in response to the user touching the display screen

ABSTRACT

The present disclosure describes imaging techniques and devices having improved autofocus capabilities. The imaging techniques can include actively illuminating a scene and determining distances over the entire scene and so that a respective distance to each object or point in the scene can be determined. Thus, distances to all objects in a scene (within a particular range) at any given instant can be stored. A preview of the image can be displayed so as to allow a user to select a region of the scene of interest. In response to the user&#39;s selection, the imager&#39;s optical assembly can be adjusted automatically, for example, to a position that corresponds to optimal image capture of objects at the particular distance of the selected region of the scene.

FIELD OF THE DISCLOSURE

The present disclosure relates to imaging devices having autofocuscontrol.

BACKGROUND

Some image acquisition devices, such as digital cameras and smartphonecameras, include an autofocus (“AF”) optical system operable to focus ona selected point or area of a scene. The AF feature can provide thedevice with the ability to focus automatically on a subject correctly,without the need for manual intervention from the user.

Various types of AF control are available, including passive control(e.g., contrast AF), and active control (e.g., Laser AF). Smartphones,for example, tend to use passive AF, because contrast is needed for thelens to focus. Such devices may have difficulty focusing on blankcolored surfaces or in low light. A flash, which is included on somesmartphones, can help produce artificial light to aid in the focusing inthese situations. Contrast AF tends to be highly iterative and thus canbe time-consuming and can use significant computational resources.Active AF, on the other hand, involves actively measuring the distanceto an object in a scene, and then adjusting the optics for proper focusof that particular object. Active AF often works well in a low-lightenvironment, but only a limited area typically is illuminated by theactive illumination. Consequently, distance information of a limitedarea in a scene is known. If a user desires another area in the scene tobe in focus, the camera or host device must retake the distancemeasurement.

SUMMARY

The present disclosure describes imaging techniques and devices havingimproved autofocus capabilities. The imaging techniques can includeactively illuminating a scene and determining distances over the entirescene and so that a respective distance to each object or point in thescene can be determined. Thus, distances to all objects in a scene(within a particular range) at any given instant can be stored. Apreview of the image can be displayed so as to allow a user to select aregion of the scene of interest. In response to the user's selection,the imager's optical assembly can be adjusted automatically, forexample, to a position that corresponds to optimal image capture ofobjects at the particular distance of the selected region of the scene.

In one aspect, for example, a method of generating an image includesdisplaying a first image on a display screen, wherein each of multipleregions of the displayed image has associated therewith a respectivedistance value. The method includes receiving input indicative of auser-selection of one of the regions of the displayed image. In responseto receiving the user input, a position of an optical assembly of animager is adjusted so that the imager is focused on one or more objectsat a distance that corresponds to the distance value associated with theuser-selected region of the displayed image.

One or more of the following features are present in someimplementations. For example, the method can include includingacquiring, by the imager, a second image while the one or more objectsat the distance that corresponds to the distance associated with theuser-selected region of the displayed image are in focus for the imager.

In some cases, the method includes calculating the respective distancevalue for each of the regions of the displayed first image based on anoptical time-of-flight technique. Further, the method can includeemitting modulated or pulsed optical radiation signals toward the scene,sensing, by a time-of-flight receiver, signals of the modulated orpulsed optical radiation reflected by one or more objects in the scene,generating output signals based on the sensed signals, calculating therespective distance value for each of the regions of the first imagebased, at least in part, on the output signals.

In some instances, receiving input indicative of a user-selectionincludes receiving a signal indicative of a user touching an area of thedisplay screen where the selected region of the image appears. In someimplementations, adjusting the position of the optical assembly isbased, at least in part, on an adjustment amount stored in a look-uptable in memory, wherein the adjustment amount corresponds to thedistance associated with the user-selected region of the displayedimage.

In another aspect, the disclosure describes an apparatus that includes ahost device comprising a display screen and operable to receive userinput. The apparatus also includes an imaging device comprising animager and a time-of-flight module. The imager is operable to acquire animage of a scene and includes an adjustable optical assembly operablefor autofocus. The time-of-flight module includes an illumination sourceto emit modulated or pulsed optical radiation, and a receiver operableto sense modulated or pulsed optical radiation reflected by one or moreobjects in the scene at a wavelength emitted by the illumination sourceand, in response to sensing the optical radiation, to generate outputsignals. One or more processors are collectively operable to cause afirst image acquired by the imager to be displayed on the displayscreen, calculate a respective distance value for each of multipleregions of the displayed image based, at least in part, on the outputsignals, and in response to input indicative of a user-selection of oneof the regions of the displayed image, adjust a position of the opticalassembly so that one or more objects, at a distance that corresponds tothe distance value associated with the user-selected region of thedisplayed image, are in focus for the imager.

In some implementations, the one or more processors are collectivelyoperable to calculate the respective distance value for each of themultiple regions of the displayed image using a time-of-flighttechnique. Further, in some instances, the display screen is aninteractive touch screen operable to receive an indication of the regionof the displayed image selected by the user for autofocus in response tothe user touching the display screen.

In accordance with another aspect, a method of generating an imageincludes displaying a first image on a display screen, wherein each ofmultiple regions of the displayed image has associated therewith arespective distance value. The method includes receiving inputindicative of a user-selection of one of the regions of the displayedimage, the selected region of the image including an object. A futureposition of an object is estimated based, at least in part, on adistance that corresponds to the distance value associated with theuser-selected region of the displayed image, and an optical assembly ofan imager is adjusted, so that object is in focus when the object is atthe future position.

In some cases, the foregoing method also includes acquiring, by theimager, a second image when the object is at the future position. Insome cases, the respective distance value for each of the regions of thedisplayed first image is calculated based on an optical time-of-flighttechnique. For example, some implementations include emitting modulatedor pulsed optical radiation signals toward the scene, sensing, by atime-of-flight receiver, signals of the modulated or pulsed opticalradiation reflected by one or more objects in the scene, generatingoutput signals based on the sensed signals, and calculating therespective distance value for each of the regions of the first imagebased, at least in part, on the output signals. In some instances,receiving input indicative of a user-selection includes receiving asignal indicative of a user touching an area of the display screen wherethe object in the image appears.

In yet another aspect, an apparatus includes a host device comprising adisplay screen and operable to receive user input. The apparatus alsoincludes an imaging device comprising an imager and a time-of-flightmodule. The imager is operable to acquire an image of a scene andincludes an adjustable optical assembly operable for autofocus. Thetime-of-flight module includes an illumination source to emit modulatedor pulsed optical radiation, and a receiver operable to sense modulatedor pulsed optical radiation reflected by one or more objects in thescene at a wavelength emitted by the illumination source and to generateoutput signals based on the sensed signals. One or more processorscollectively are operable to cause a first image acquired by the imagerto be displayed on the display screen, and calculate a respectivedistance value for each of multiple regions of the displayed imagebased, at least in part, on the output signals. In response to inputindicative of a user-selection of one of the regions of the displayedimage, where the selected region of the image includes an object, theone or more processors estimate a future position of the object based,at least in part, on a distance that corresponds to the distance valueassociated with the user-selected region of the displayed image. The oneor more processor adjust the optical assembly so that the object is infocus for the imager when the object is at the future position.

In some implementations, the one or more processors are collectivelyoperable to calculate the respective distance value for each of themultiple regions of the displayed image using a time-of-flighttechnique. The display screen can be, for example, an interactive touchscreen operable to receive an indication of the region of the displayedimage selected by the user for autofocus in response to the usertouching the display screen.

Other aspects, features and advantages will be readily apparent from thefollowing detailed description, the accompanying drawings, and theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of an imaging device.

FIG. 2 illustrates an example of a host device displaying an imageacquired by the imaging device.

FIG. 3 is a flow chart showing an example of a method for autofocus.

FIG. 4 illustrates another example of an imaging device.

FIGS. 5A, 5B and 5C illustrate an example of a host device displaying asequence of images acquired by the imaging device.

DETAILED DESCRIPTION

The present disclosure describes imaging techniques and devices havingimproved autofocus capabilities. The imaging techniques include activelyilluminating a scene and determining distances over the entire scene andso that a respective distance to each object or point in the scene canbe determined. Thus, distances to all objects in a scene (within aparticular range) at any given instant can be stored. A preview of theimage can be displayed so as to allow a user to select a region of thescene of interest. In response to the user's selection, the imager'soptical assembly can be adjusted automatically, for example, to aposition that corresponds to optimal image capture of objects at theparticular distance of the selected region of the scene.

As shown in FIG. 1, an imaging device 100 includes a primary imager 102having an optical assembly 104 that includes one or more lenses whosepositions can be adjusted (e.g., by an actuator such as a motor or MEMsactuator) to achieve autofocus. Imager 102 is operable to acquire imagesof a scene 120 that includes one or more objects 122, 124. The imager102 may have a relatively large number of pixels (e.g., an array of30×40 pixels) so as to be capable of acquiring relatively highresolution images. In some instances, the imager 102 is implementedusing CCD or CMOS sensor technology.

The imaging device 100 also includes a time-of-flight (“TOF”) module110, which has an illumination source 112 and an optical receiver 114operable to detect a wavelength (or range of wavelengths) of radiationemitted by the illumination source 112. Thus, in some instances, theillumination source 112 is operable to emit pulsed or other modulatedelectro-magnetic radiation. For example, some implementations use adirect TOF technique in which single pulses of radiation are emitted bythe illumination source 112, and the receiver 114 detects the rising andfalling edges of the pulses and provides time stamps for the detectededges. In such implementations, the time-of-flight can be determined bymeasuring the time between the emission of a light pulse and its arrivalafter reflection by an object in the scene.

Other implementations can use a phase shift, or indirect, TOF technique.For example, the illumination source 112 can be operable to emitmodulated infra-red (“IR”) radiation, and the receiver 114 can includean array of TOF demodulation pixels operable to detect IR radiationreflected by the objects 122, 124 and to demodulate the detectedsignals. In operation, modulated light emitted by the illuminationsource 112 through optics assembly 116 is directed toward the scene 120.A fraction of the total optical power directed to the scene 120 isreflected back to the TOF module 110, through optics assembly 118, andis detected by demodulation pixels in the receiver 114. Each pixel inthe receiver 114 is operable to demodulate the impinging light signalthat is collected by the optics assembly 118 (e.g., a lens). Thedemodulation values allow for each pixel to compute the time-of-flight,which, in turn, directly corresponds to the distance information (R) ofthe corresponding point in the scene 120. The time-of-flight can beobtained by demodulating the light signals reflected from the scene 120and that impinge on the active pixels of the receiver 114. Various knownmodulation techniques can be used, such as pseudo-noise modulation,pulse modulation or continuous modulation. The distance to the objectfor each pixel then can be calculated based on the detected signalsusing known techniques. The distance information for each pixel (oraverage values for respective sub-groups of the pixels) can be stored,for example, in memory 132.

The illumination source 112 can be implemented, for example, as a lightemitting diode (LED), infra-red (IR) LED, organic LED (OLED), infra-red(IR) laser or vertical cavity surface emitting laser (VCSEL). Thereceiver 114 can be implemented, for example, as an N×M arrayIR-sensitive pixels. If the phase shift, or indirect, TOF technique isused, then the receiver 114 can include an array of demodulation pixels.In some instances, the array is relatively small (e.g., 3×3 pixels);although different numbers of pixels can be used for someimplementations (e.g., an array of 30×40 pixels).

An electronics control unit (ECU) 130, which can include control,decoder, read-out circuitry as well as processing and other logic (e.g.,microprocessor and/or other circuitry), can control the timing of theillumination source 112 and receiver 114 to enable its synchronousdetection. The ECU 130 can be implemented, for example, as one or moreprocessor chips (e.g., a microprocessor) configured with hardware logicand/or software instructions to perform the tasks described here. TheECU 130, the imager 102 and the TOF module 110 can be mounted, forexample, on a printed circuit board in the host device.

Preferably, the field-of-view (“FOV”) of the imager 102 and the TOFmodule 110 substantially overlap one another.

The imager 102 and TOF module 110 can be incorporated into a host device(e.g., a smart phone, mobile phone, tablet, personal data assistant,notebook computer) with suitable power resources, and processingcircuitry. A user can activate the imaging device 100 to acquire animage, for example, by pushing an appropriate button on the host deviceor by tapping on an appropriate icon on an interactive display screen(e.g., a touch screen) 204 of the host device 200 (FIG. 2). In response,a preview of the image 202 acquired by the primary imager 102 isdisplayed on the display screen 204 of the host device 200. In someinstances, the preview image 202 may be relatively coarse and/orportions of the previewed image of interest to the user may be slightlyout of focus. The user, however, can select a particular region of theimage (or a particular object in the image) that she wants to bein-focus. The user can perform the selection, for example, by touchingthe area of the display screen 204 where the object or region ofinterest is displayed. For example, if the user wants the object 124A tobe in focus, she would touch one of the areas A, B of the display screen204 where the object 124A appears.

In the illustrated example of FIG. 2, each region of the image 202 isassociated with a respective distance value based on previouslycalculated and stored values for the image. Assuming, for example, thatthe TOF receiver 114 includes an array of 3×3 pixels for a total of ninedemodulation pixels, the display screen 204 can be divided into the samenumber (i.e., 9) regions, each of which is associated with a respectiveone of the pixels. Each region (A though I) of the display screen 204 isthus associated with a respective distance value based on the previouslycalculated and stored values for the acquired image. In some instances,a grid 206 indicating the various regions (A though I) can be overlaidon the displayed image 202. In some implementations, the image isdisplayed without such a grid.

In some cases, to provide for greater resolution, the receiver 114 mayhave a greater number of pixels (e.g., an array of 30×40). If eachregion of the image 202 is associated with a single pixel, then therewould be a greater number of user-selectable regions of the image 202.In some instances, the pixels form non-overlapping sub-groups, each ofwhich includes pixels that are adjacent one another. Each region of theimage 202 then corresponds to a respective one of the sub-groups ofpixels. In such cases, the distance value associated with a particularregion can be, for example, the average distance value for all thepixels in the sub-group.

To select a particular object or area of the image 202 for autofocus,the user touches (e.g., with her finger or a stylus) the region of thedisplay screen 204 in which the particular object or area of thepreviewed image appears. Thus, for example, if the user wants theimaging device 100 to capture an image in which the object 124A is infocus, she would touch region A or region B of the display screen 204where the object 124A appears. In response, the ECU 130 generates one ormore signals to adjust the position of the optics assembly 104 in theimager 102 so that objects in the scene 120 at a distance correspondingto the previously stored value for the selected region are in-focus. Theautofocus mechanism 105 thus focuses the optical assembly 104 accordingto the distance to the part of the scene associated with the region ofthe display selected by the user. Distances can be correlated with, forexample, pre-set focus information for the optical assembly 104. Thefocus information can be stored, for example, in a look-up table (“LUT”)134 in memory.

When the user again activates the imaging device 100 to capture animage, the optics assembly 104 in the imager 102 will be positioned suchthat objects located at a distance corresponding to the user-selectedportion of the scene 120 are in focus. In some cases, the user may notneed to reactivate the imaging device by pushing a button on the hostdevice or by tapping on an icon on the interactive display screen of thehost device another time. Instead, the imaging device 100 can beconfigured to capture the autofocused image as soon as the opticsassembly 104 is adjusted, without the need for further user input.

FIG. 3 is a flow chart of a method according to some implementations. Asindicated by 150, a scene is illuminated by the TOF illumination source112. The TOF receiver 114 collects light (e.g., IR) reflected by one ormore objects in the scene (152), and the demodulated (or other sensed)signals are used to determine distance values to multiple points in thescene (154). The primary imager 102 also acquires an image of the scene(156). The image acquired by the imager 102 is displayed on aninteractive display screen of a host device (158), and each of variousregions of the displayed image is associated with one of thepreviously-calculated distance values (160). A user then can select oneof the regions of the displayed image using, for example, theinteractive displays screen (162). The imager 102 adjusts the opticalassembly 104 so that it autofocuses on objects at a distance thatcorresponds to the distance associated with the user-selected region ofthe displayed image (164). The imager 102 then captures another imagesuch that objects at the distance corresponding to the distanceassociated with the user-selected region of the displayed image are infocus (166).

The foregoing techniques can, in some cases, be executed more rapidlyrelative to contrast AF techniques, and may require fewer computationalresources.

In some implementations, the autofocus imaging device 100 is operable tocollect distance data of a scene over a 0.1 m-1.5 m range (as measuredfrom the device 100). In other implementations, the device 100 isoperable to collect distance data over larger distances (e.g., up to 3meters or more) by aggregating charges incident on several pixels.

The imaging device 100 can be operable in other passive and/or activemodes when objects in a scene are outside of the specified ranges. Forexample, the TOF illumination source 112 can be operable to switch to astructured light mode, and distance data to objects in a scene can becalculated using the structured light. Further, in some modes ofoperation, the imaging device 100 can be configured to determine properfocus using a contrast AF technique.

The techniques described here can be used not only for still images, butalso for video images. FIG. 4 illustrates an example of a scene 320 inwhich an object 322 is moving from a first position to a second positionand then to a third position. In this example, it is assumed that aninitial image is acquired at time t1, when the object 322 is at a firstposition. The acquired image is displayed on an interactive displayscreen 204 of a host device 200 (e.g., a smart phone). A user can selecta particular object in the displayed image 302 (FIG. 5A) that she wantsto be in-focus, for example, by touching the corresponding part of theinteractive display screen 204 with her finger or with a stylus. Forexample, to select the object 322, the user would touch region I on thedisplay screen 204. The ECU 130 then can use frame-to-frame tracking,for example, to track the position of the selected object 322A in theimager's field of view. At a subsequent time t2, when the object 322 isat a second position in the scene 320, another image is captured. Usingframe-to-frame tracking, the ECU 130 can determine that the trackedobject 322A now appears in region E of the displayed image 302A (seeFIG. 5B).

Each time an image is captured, the TOF module 100 generates distancedata for multiple points in the image. Thus, each region (A through I)of the displayed image is associated with corresponding distance data,which indicates the distance from the imaging device 100 to the objectsin the scene 320. The ECU 130 can use the time between distancemeasurements, and the distances to the object 322 measured at the firstand second positions, to calculate the real or relative speed and/orvelocity of the object. This information can be used by the ECU 130 topredict a trajectory and future position of the tracked object 322 andto adjust the focus of the imager's optical assembly 104 such that whenthe tracked object reaches the third position at time t3, the imager'soptical assembly will be in focus for the tracked object.

The foregoing techniques can, in some cases, be executed more rapidlyrelative to contrast AF techniques, and may require fewer computationalresources. Further, because the present techniques can be executed morequickly, they can help reduce the amount of blur in the displayedimage(s) (see FIG. 5C, showing the displayed image at time t3).

Various aspects of the subject matter and the functional operationsdescribed in this specification can be implemented in digital electroniccircuitry, or in computer software, firmware, or hardware, including thestructures disclosed in this specification and their structuralequivalents, or in combinations of one or more of them. Embodiments ofthe subject matter described in this specification can be implemented asone or more computer program products, i.e., one or more modules ofcomputer program instructions encoded on a computer readable medium forexecution by, or to control the operation of, data processing apparatus.The computer readable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, a composition ofmatter effecting a machine-readable propagated signal, or a combinationof one or more of them. The terms “data processing apparatus” and“computer” encompasses all apparatus, devices, and machines forprocessing data, including by way of example a programmable processor, acomputer, or multiple processors or computers. The apparatus caninclude, in addition to hardware, code that creates an executionenvironment for the computer program in question, e.g., code thatconstitutes processor firmware, a protocol stack, a database managementsystem, an operating system, or a combination of one or more of them.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. A computer can be embedded in anotherdevice, e.g., a mobile telephone or a personal digital assistant (PDA),to name just a few. Computer readable media suitable for storingcomputer program instructions and data include all forms of non-volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks;magneto optical disks; and CD ROM and DVD-ROM disks. The processor andthe memory can be supplemented by, or incorporated in, special purposelogic circuitry.

To provide for interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving a display device, e.g., a CRT (cathode ray tube) or LCD (liquidcrystal display) monitor, for displaying information to the user and akeyboard and a pointing device, e.g., a mouse or a trackball, by whichthe user can provide input to the computer. Other kinds of devices canbe used to provide for interaction with a user as well; for example,feedback provided to the user can be any form of sensory feedback, e.g.,visual feedback, auditory feedback, or tactile feedback; and input fromthe user can be received in any form, including acoustic, speech, ortactile input.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the invention or of what may beclaimed, but rather as descriptions of features specific to particularembodiments of the invention. Certain features that are described inthis specification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable subcombination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

Accordingly, various modifications can be made to the foregoingexamples, and other implementations are within the scope of the claims.

What is claimed is:
 1. An apparatus comprising: a host device comprisinga display screen, the display screen being an interactive touch screenoperable to receive an indication of a region of a displayed imageselected by a user for autofocus in response to the user touching thedisplay screen; and an imaging device including: an imager operable toacquire an image of a scene, the imager including an adjustable opticalassembly operable for the autofocus; a time-of-flight module including:an illumination source to emit modulated or pulsed optical radiation,and a receiver operable to sense the modulated or the pulsed opticalradiation after the modulated or the pulsed optical radiation has beenreflected by one or more objects in the scene at a wavelength emitted bythe illumination source and, in response to sensing the opticalradiation, to generate output signals; an electronic control unitoperable to: cause a first image acquired by the imager to be displayedon the display screen, calculate, using a time-of-flight technique, arespective distance value for each of multiple regions of the displayedimage based, at least in part, on the output signals from thetime-of-flight module; and in response to an interaction with thedisplay screen indicative of a user-selection of one of the regions ofthe displayed image, adjust a position of the optical assembly so thatone or more of the objects, at a distance that corresponds to thedistance value associated with the user-selected region of the displayedimage selected by the user, are in focus in an image displayed by theimager.
 2. The apparatus of claim 1 wherein the adjustable opticalassembly includes one or more lenses whose positions are adjustable byan actuator.
 3. The apparatus of claim 1 wherein the illumination sourceis operable to emit the pulsed optical radiation, and the receiver isoperable to detect rising and/or falling edges of the pulsed opticalradiation after the pulsed optical radiation has been reflected by theone or more objects in the scene, the receiver further being operable toprovide time stamps for the detected rising and/or falling edges.
 4. Theapparatus of claim 3 the electronic control unit is operable todetermine a time-of-flight by measuring a time between emission of anoptical radiation pulse emitted by the illumination source and arrivalof the optical radiation pulse after reflection of the optical radiationpulse by the one or more objects.
 5. The apparatus of claim 1 wherein:the illumination source is operable to emit modulated infra-redradiation, and the receiver includes an array of time-of-flightdemodulation pixels operable to sense infra-red radiation reflected bythe one or more objects and to demodulate signals representing theinfra-red radiation.
 6. The apparatus of claim 1 wherein, in operation,modulated light emitted by the illumination source through an opticsassembly is directed toward the scene, and wherein optical radiationreflected by the one or more objects to the time-of-flight modulethrough the optics assembly is detected by demodulation pixels in thereceiver, each of the demodulation pixels being operable to demodulatesignals corresponding to the optical radiation.
 7. The apparatus ofclaim 6 wherein the receiver includes a M×N array of pixels, where eachof M and N is greater than 1, each of the pixels being associated with adifferent respective region of the interactive touch screen, wherein theelectronic control unit is operable to associate each respective regionof the interactive touch screen with a respective distance value basedon the calculated distance values for the displayed image.
 8. Theapparatus of claim 7 wherein the electronic control unit is operable tocause a grid to be overlaid on the displayed image, the grid indicatingthe respective regions of the interactive touch screen corresponding tothe respective distance values.
 9. The apparatus of claim 1 including aprinted circuit board in the host device, wherein the electronic controlunit, the imager and time-of-flight module are mounted on the printedcircuit board.
 10. The apparatus of claim 9 wherein the host device issmart phone.
 11. The apparatus of claim 1 wherein the electronic controlunit is operable to: cause a preview of an image of the scene acquiredby the imager to be displayed on the interactive touch screen, and inresponse to the user selecting a particular region of the preview of theimage, to adjust a position of the optical assembly so that featuresdisplayed in the particular region of the preview of the image are infocus.
 12. The apparatus of claim 1 including memory that storescorrelations between distance values and focus information for theoptical assembly.
 13. The apparatus of claim 12 wherein the focusinformation is stored in a look-up table in the memory.
 14. Theapparatus of claim 13 wherein the electronic control unit is operable toadjust the position of the optical assembly is based, at least in part,on an adjustment amount stored in the look-up table, wherein theadjustment amount corresponds to a distance value associated with auser-selected region of the displayed image.
 15. The apparatus of claim1 wherein the imaging device is operable to acquire automatically anautofocused image after adjustment of the optical assembly.